Carburetor



Patented Jan. 10, 1933 UNITED STATES lwr-lazN'ly OFFICE HERBERT H. TBAI), F VANCOUVER, BB'I'JTl'SHJ COLUMBIA, CANADA.. ASSIGNOB T0 MOTOR DllVllGES, INCORPORATED, 0F ELINOIS CHICAGO, ILLINOIS, CORPORATION OF CABBUBETOR This invention relates to improvementsv in fuel mixing and conveying systems for internal combustion engines and it consists of the matters hereinafter described and more particularly pointed out in the appended claims.

The primary object of the invention is to provide a system of the kind mentioned for forming an evenly proportioned mixlo ture and for conveying the'same in a downward direction tothe inlet side of the engine cylinders.

Another object of the invention is to provide a system of this kind comprising a manifold and a liquid rfuel and air mixing device disposed above themanifold so that after the fuel and air are mixed together, the path of the mixture is alwaysdownward, whereby its travel is assisted by the action of gravity.

A further obj ect of the invention is to provide a system of this kind, whereby the larger particles of liquid fuel'drop out of the air stream to be vaporized for reentrance and further intermixing therewith.

Still another object of the` invention vis to provide ina system of this kind, a combined inlet and exhaust manifold wherein the exhaust outlet is centrally disposed which allows of an even exhausting from the cylinders with a corresponding reduction in back pressures.

. These objects of the invention as well as others, to ether with the `many advantages thereof, will more fully appear as I proceed with my specification.

Inthe drawing Fig. 1 is a view partly in side elevation and partly in longitudinal section of a fuel mixing and conveying system embodying my invention.

Fig. 2 is a vertical sectional view through the same as takenon the line 2--2 of Fig. 1. Fig. 3 is a detail horizontal sectional view through the same as taken on the line 3--3 of Fig. 1. g

Referring now in detail to that embodiment of the invention illustrated in the accompanying drawing 1 indicates as a whole the cylinder block of an internal combustion engine of the four cylinder type and 1929. serial No. l375.1611.

2 indicates the cylinder head therefor. 3 indicates as 'a whole aA one piece combined inlet and exhaust manifold. and 4 indicates as a whole a fuel and air mixing device in the nature of a carburetor, disposed above the manifold.

The manifold includes an inlet portion I having oppositely and downwardly diverging branches 5-5 extending parallel with the cylinder head, with a centrally disposedV common inlet boss 6 at the top thereof. The outlet ends 7-7 of said branches which are disposed at the lowest point thereof extend at a right angle to the plane of said branches,

and are made integral with the back iange 8 of the manifold. The exhaust portion of the manifold comprises a centrally disposed chamber like body 9 and oppositely disposed branches 10--10, arranged in the plane of but below the inlet branches 5 5. At the bottom end of said body is an outlet boss 11v preferably arranged coaxially with respect to the inlet boss 6, said outlet boss being formed for attachment to an exhaust pipe 12 whereby the spent gases are conducted to a point spaced from the engine forA discharge toatmosnhere. i

The ton wall of the chamber like body 9 is formed bv the junction of the bottom portions of the inlet branches; and in said junction isformed a slight concavity ordepression 13 in line with the inlet to said branches. The inlet end 14 of each exhaust branch 10 is curved upwardly and inwardly to terminate in the plane'of the outlet ends of the inlet branches whereby they too join the back ange 8. A third exhaust outlet 15 is provided which is disposed in the body 9 as best shown in Fig. 1. In the back'flange 8 are suitable openings, disposed between the various branch ends to receive the usual lag screws or bolts 16 for attaching the manifold as a whole to the cylinder head. If desired ay suitable gasket (not shown herein) may be disposed between the cylinder head and said back iange. In this respect it is v pointed out that each inlet branch 5 serves two' cylinders each while each exhaust branch 10 serves an endmost cylinder andthe third top end portion outlet serves the two engine. Y

The fuel and air mixing device 4 which as before mentioned is in the form of a carburetor includes an upright tubular body 17 having an interior bore 18'. The bottom end of said body is flanged to seat upon and be secured to boss 6 of the manifold as by the bolts 19 while operatively connected 'to the top end of said body so as to open into said bore is an air inlet 20 in the form of an elbow. In the bore 18 of the body isformed an annular shoulder 21 upon which is seated a Venturi tube made up of top and bottom spaced sections 22 and 23 respectively. The of the bottom section of the Venturi tube is reduced in diameter to there form an annular chamber 24 opening into the interior of the Venturi tube by an inwardly and downwardly tapering annular space 25. In the bottom end or neck of the body 17 is a disc like throttle valve 26 of the usual kind and by which the amount and velocity of the incoming air is controlled.

Spaced laterally to one side of the body is a fuel reservoir 27 having a bottom inlet 28 controlled in the usual manner by a float valve 29. In said body between its central bore and said reservoir is a chamber or bore 30 having a lunger or piston 31 reciprocable therein. K port 27 a connects the bottom of middle cylinders of the the reservoir with the bottom of the chamber -34 together in the or bore 30 while a second port 32 disposed in a plane above that of the port ,27a connects sald chamber or bore with the annular chamber 24 before mentioned. Preferably the plunger 31 is so connected up with the throttle 26 that when the throttle is opened, the plunger is depressed and when the throttle is closed down said plunger is elevated.

In that side of the body, opposite the reservoir are formed vertically disposed, inner and outer passageways 33 and 34 respectively. The inner passageway connects at its bottom end with the annular chamber 24 by means of a port33 while the bottom end of the outer passageway opens by a port 35 into the bottom end of the body just above one side of the throttle when it is in its closed position. A port 36 connects the passageways 33 and plane of the knife blade like top edge of the body section 21 of the Venturi tube, which edge is coincident with the normal level of fuel in the reservoir. The passageway 34 opens near its top end to atmosphere by a port 34a and the passage of air through this port is controlled by an adjusting screw 37.

Assume that the engine is in operatlon and is running at idling speed with the throttle valve substantially closed. With the fuel level substantially flush with the top edge of the Venturi tube section 21, ent that the same fuel level is attained in the chamber 30, ,n annular chamber 24, and

it is apparpassageway 33 respectively. At such idling' unmixed particles of fuel drain out of saidl passa eway to fall into the recess 13 in the mani old. This recess being subjected to the heat of the exhaust gases constitutes a hot spot so that such unmixed fuel that falls thereon is vaporized to intermix with the mixture entering the inlet manifold to be delivered as a dry combustible gas tothe engine cylinders, by the branches 5-5. Y

To increase engine speed, the throttle 26 is opened in the usual manner and as the plunger or piston 31 is connected thereto as before mentioned, said plunger will move downwardly in the bore 30 displacin the fuel therein. This displacement of the uel in said bore raises the level of the fuel in the annular chamber 24 so that a portion of said fuel flows over the sharp annular top edge of the tube section 21 into the taperin passageway 25 and another portion of sa1d fuel is forced back-through the port 27'L into the reservoir 27 to vraise the level therein. lThis displacement is advantageous because it cleans out the port 27a of any sediment tending to chokev the same and it facilitates the admission of fuel into the inlet manifold for acceleration purposes after which the stant and is controlled by said port.

When the engine4 is running under open throttle say at a reasonably high speed, the chamber 30 becomes depleted so that fuel passes from the reservoir directly to the annular space 24 to be mixed with incoming air and then pass down through the Venturi tube to the inlet manifold. Should the throttle 26 be opened wider, the plunger 31 becomes ineffective in its further movement because of the absence'of fuel in the bore 30. Thus there is no waste of fuel at this time of such further acceleration as it is not desirous to further enrich the mixture.

From the 'above it is apparent that the plunger acts as a displacement plunger and not asa pump plunger as in carburetors as now made, and therefor such a displacement plunger 'is only effective at moderate speeds because at high speeds, there is no fuel in the bore 30 to displace. This feature provides for an economy in fuel and is indeed effective fuel supply is conin accelerating from a. low idling' speed up to a predetermined moderate It is apparent from the foregoing, that after the fuel passes through the port 36 at idling speed -or passes through the annular space 25 at-higher speed, it in both instances mixes with incoming air and the direction or passage of the mixture is always thereafter downwardly to the engine cylinders. Thus the natural force of gravity cooperates with the suction action of the engine while functioning to convey the mixture to the cylinders, the same resulting in a saving of fuel and better accelerating action.

Again it will be noticed that the throttle is located below the plane of any fuel inlet to the mixing device, so that any fuel after leaving the same must pass said throttle, and this in a downward direction. Thus the engine becomes more responsive to the throttle and the number of parts movable or otherwise necessary in the mixing device is reduced to a minimum.

While in describing my invention, I have referred in detail to the form arrangement and construction of the various parts thereof, the same is to be considered merely as illustrat-ive so that I do not wish to be limited thereto except as may be specifically set forth in the appended claims.

`I claim as my invention 1. In a fuel and air mixing device, a body having a perpendicularly disposed air passageway therein, a Venturi tube in said passageway having an annular chamber about a portion of the same and having a downwardly and inwardly directed passage connecting said chamber and passageway, a throttle valve in said air passageway below said Venturi tube, a fuel reservoir connected to said chamber means providing a fuel passageway opening at-its bottom into said air passageway in the vicinity of said throttle valve, said fuel passageway communicating at its top end with said annular chamber and also opening to atmosphere and means between said chamber and the fuel reservoir for changing the fuel level therein by displacement of a portion of said fuel,

2. In a fuel and air mixing device, a body having a perpendicular air passageway therein, a Venturi tube disposed in said passageway and having an annular chamber about a portion of the same and having a downwardly and inwardly directed passage connecting said chamber and passageway, a throttle valve in said air passageway below said Venturi tube, a fuel reservoir spaced from said passageway, there being a bore arranged parallel with 'said passageway and between the same and said fuel reservoir and communicating with both, means providing a fuel passageway opening at its bottom into said air passageway in the vicinity of said throttle valve, said fuel passageway communicating at substantially its top end with said annular chamber and also opening to atmosphere and a plunger in said bore between said passageway and fuel reservoir for displacing fuel therefrom for raising the level ofthe fuel in said annular chamber.

In witness whereof I have hereunto set my hand, this 21st day of June, 1929.

HERBERT H. TRAIL. 

